The present invention relates to a testing apparatus for the purpose of testing for defects in liquid crystal display substrates used in liquid crystal display panels and the like.
The so-called active matrix system has been used in the realization of liquid crystal display panels having a high number of pixels which are used in liquid crystal televisions, or the like. These have a construction which is provided with switching circuits which operate by means of the thin film transistors of the various pixels; the number of pixels generally reaches 250,000 to 500,000, and units with more than 1,000,000 have reached the marketplace.
Conventionally, in the manufacturing of liquid crystal display panels of this type of active matrix type, a process has been used in which pixel electrodes corresponding to each pixel are formed in a matrix on a substrate of glass or the like, gate lines and source lines are connected to each of these pixel electrodes. Thin film transistors are then formed, corresponding to each of the pixel electrodes. An active matrix liquid crystal display substrate (hereinafter "liquid crystal substrate") is thus manufactured. A transparent substrate is then disposed above this liquid crystal substrate and facing it, separated by a small space, and the space filled with liquid crystal.